Multicomponent or monocomponent vaccine to be used against chagas disease, pharmaceutical compositions containing them, procedure for the obtention of immunogen of said vaccines, and nucleic acid used in said procedure

ABSTRACT

A monocomponent vaccine effective to moderate the clinical consequences of Chages disease, capable of stimulating an immune response against the trans-sialidase virulence factor of the  Trypanosoma cruzi  parasite. The vaccine active ingredient is an immunogenic component with a polynucleotide encoding one or more polypeptide(s) which includes a C-terminal region composed of at least two repetitive units of amino acids, with a polypeptide with trans-sialidase activity of  Trypanosoma cruzi  fused to the C-terminal region. The vaccine further comprises an aluminum oxide adjuvant that does not inhibit trans-sialidase enzymatic activity of the immunogen portion.

The technical objective of this invention is to strengthen the immune response against protozoan and bacterial antigens, especially to increase the induction of the cytotoxic T response, essential against these antigens. This invention will lead to the development of therapeutic or prophylactic vaccine formulations for the Chagas disease.

STATE OF THE ART

Trypanosoma cruzi is a protozoan of the Kinetoplastida order, Tryponosomatidae family, distinguished by the presence of a single flagellum and a single mitochondrion, within which its genome is ordered in a complex and compact network called kinetoplast. It is an intracellular parasite with a life cycle involving vertebrates and invertebrates.

There are three different forms: Amastigote: spherical or oval, it is the reproductive form in the interior of the mammal cells, Epimastigote: elongated, with the kinetoplast located anterior to the nucleus, it is the reproductive form in the digestive tract of invertebrates and in culture media, and Trypomastigote: also elongated, but with the kinetoplast located posterior to the nucleus. Found in the mammals blood and is their infecting form. This form is not divided.

T. cruzi is divided in two large groups: T. cruzi I and T. cruzi II. The latter is divided into five smaller groups: T. cruzi IIa, IIb, IIc, IId and IIe.

The Chagas disease etiologic agent also known as American tripanosomiasis is a protozoan intracellular parasite, Trypanosoma cruzi. It is transmitted by a hematophagous insect, the Triatoma infestans, which transmits the parasite when the insect defecates on the bite wound as it feeds. On mammals the cycle of T. cruzi cycles between trypomastigote stage which circulates in the blood and the amastigote stage which replicates in the cytoplasm of infected host cells (especially on muscles). Chagas disease prevails in most Latin American countries including Mexico and Central America, where approximately 18 million people are infected with T. cruzi and at least 50.000 children and adults die every year from chronic Chagas disease due to lack of effective treatments.

The reduvid triatoma, known as vinchuca (from Ecuador to Patagonia), chipo (in Venezuela), pito (in Colombia), and barbeiro (in Brazil) are hematophagous insects, that is to say, blood suckers, that live in cracks, holes and dirty areas in houses or cellars in South America and Central America regions. They become infected after biting an animal or person that already suffers from the disease. In general, the infection is spread to human beings when an infected insect deposits feces on a person's skin while the person is sleeping at night.

The person often rubs the bite accidentally introducing feces in the bite wound, an open cut, eyes or mouth. Animals can also be infected in the same way and also contract the disease eating the infected insect. The infected person may not present symptoms of the disease until 10 or 15 years after being infected; this makes the detection of the disease even more difficult.

More than 90 million people are at risk of infection in endemic areas. In addition, in the endemic areas, 2-5% of fetus carried by infected mothers are aborted or born with the congenital Chagas disease.

Loss of revenue in terms of productivity lost due to sickness and high medical costs have an overwhelming effect in the economic growth of these countries. The risk of transmission of T. cruzi to non-infected individuals through organ transplants and blood transfusions from infected immigrant donors is very high.

Chemotherapeutical treatments have been partially successful in controlling T. cruzi infection and Chagas disease. However, the high toxicity of drugs and poor efficacy of available therapeutics has limited the use of chemotherapy for treatment of both acute and chronic patients. Further, drug therapy reduces the severity of disease in chronically infected individuals but cannot reverse the damage already done by parasites.

There are practically no vaccines for the prevention or treatment of the T. cruzi infection. Traditional vaccines constituted of heat-inactivated parasites, or subcellular fractions of the T. cruzi provide a degree of protection for T. cruzi infections (M. Basombrio, Exp. Parasitol. 71:1-8 (1990); A. Ruiz et al., Mol. Biochem. Parasitol, 39:117-125. (1990)). However, these vaccines fail to elicit the protective level of immunity, probably due to loss of important epitopes during inactivation and/or the failure of the antigens to enter the Major Histocompatibility Complex (MHC) class I pathway of antigen processing and presentation, and to elicit cell mediated immune responses (J. Mónaco. Immunol. Today 13:173-179 (1992)). Live attenuated vaccines are capable of entering the MHC class I pathway and might elicit protective immune responses. However, the danger of reversion of the attenuated parasites to virulent strains if attenuation is not been completed renders these vaccines impracticable. A DNA vaccine containing the gene codifying a trans-sialidase has been shown to provide prophylactic protection against T. cruzi infections in mice (F. Costa et al, Vaccine 16:768-774 (1998)), but has not been shown to prevent or reverse disease or to stimulate a CD8+ T cell response in animals. In addition, the specific cellular and humoral immune response in BALB/c mice immunized with an expression genomic library of the T. cruzi was observed (E. Alberti et al., Vaccine 16:608-612 (1998)).

Trans-sialidase is a Trypanosoma cruzi enzyme (agent that causes Chagas disease) required by this parasite to invade cells of the human host. Given the fact that if the parasite does not invade cells, it will not survive in humans, trans-sialidase seems the ideal target for an immunological attack, that is, to develop a vaccine. Therefore, the objective is a vaccine that as a response when used to immunize, may produce antibodies specifically inhibiting the trans-sialidase.

There are several trans-sialidases produced in the trypanosome. Some have only one region required for the enzymatic activity (the trans-sialidation which is the transfer of a sugar called sialic acid). Others, in addition to this region have a second region not related to trans-sialidation but that is very immunogenic (it generates antibodies in the host). This second region is called SAPA (Shed-acude-phase-antigen) and is formed by repetitive units of amino acids.

The gens (nucleic acids, DNA, formed by units called nucleotides or bases, a region of the DNA that codifyings a protein as in this case trans-sialidase, is called gen) codifying the region with enzymatic activity and the SAPA region have been identified.

One of the T. cruzi molecules described as essential for the host cell invasion is the sialic acid (Schenkman S. Et al. Cell 65, 1117-1126, 1991; Schenkman, S. et al. Ann. Rev. Microbiol. 48, 499-523, 1994; Schenkman, S. and Eichinger, D. Parasitology Today 9, 218-222, 1993). Since trypanosome is unable to synthesize sialic acid (Schauer, R. y et al. Z. Physiol. Chem. 364: 1053-1057, 1983), it must obtain it from molecules containing sialic acid present in the environment. This process is accomplished using a unique enzyme called trans-sialidase (Previato, J. O. et. al., Mol. Biochem. Parasitol. 16:8596, 1985 Y Zingales, B., et al., Mol. Biochem. Parasitol. 26, 135-144, 1987). Trans-sialidase is capable of transferring sialic acid from sialydated molecules present in the environment, such as some molecules found in the blood of the infected host, to molecules present on the trypanosome surface.

Trypanosome molecules that can be sialylated are those called mucins (Ruiz, R. C., et al. Parasite Immunol. 15,121-12, 1993; M. B. Reyes, et al. Gene 140, 139-140, 1994; J. M. Di Noia et al. J. Biol. Chem. 270, 24146-24149, 1995; J. M. Di Noia, et al. J. Biol. Chem. 271, 32078-32083, 1996). Once sialylated, mucins are the molecules that interact with the surface of the human cell to be invaded, facilitating the infection process (Ruiz, R. C., et al. Parasite Immunol. 15, 121-12, 1993). Other groups have demonstrated that if the parasite does not express trans-sialidase, it cannot infect cells in the same way as parasites containing trans-sialidase do (Pereira et al., Infect. Immum. 64, 38843892, 1996). Therefore, immunization with trans-sialidase made in such a way that generates antibodies to inhibit the enzyme, constitutes a useful tool to obtain a vaccine against this parasite. Recently it has been demonstrated that the immune response against trans-sialidase is a factor that helps prevent death of the host caused by the parasite ((Chuenkova, M. y Pereira M. E. A., J. Exp. Med. 181, 1693-1703, 1995).

Trypanosoma cruzi has two types of trans-sialidases. One type contains only the amino acids required for the activity of trans-sialidase (Briones, M. R. S. et al. Mol. Biochem. Parasitol. 70: 9-17, 1995) and was used in the application WO 9318787 with the purpose to synthesize carbohydrates due to its enzymatic activity and was proposed in second place as an immunogen in the same patent application. A second group of trans-sialidases contains, in addition to these sequences, a series of amino acid repetitions in the terminal carboxyl region called SAPA (C. Ibáñez, et al. Mol. Biochem. Parasitol. 30: 27-34, 1988; J. L. Affranchino, et al. Mol. Biochem. Parasitol 34: 221228, 1989; Cazzulo, J. J. and Frasch, A. C. C. FASEB J. 6, 3259326, 1992). This second region is highly antigenic during a natural infection in humans (M. B. Reyes, et al., Proc. Natl. Acad. Sci. USA 87:2846-2850, 1990).

The broader investigations for vaccines have been focused on attempts to develop prophylactic protein vaccines against the infection of T. cruzi, but have been carried out with little success. The development of vaccines of subunits composed by defined antigens capable of inducing strong humoral and class 1 T cell responses and of reducing the parasite burden, has been hindered due to lack of knowledge of biology of the three developing stages of the T. cruzi, the absence of sufficient information of the sequence on gens expressed in the contagious and intracellular stages, and the scientific view that chronic disease is not related to persistent parasite infection but it is the result of a parasite-induced autoimmune response.

SUMMARY OF THE INVENTION

The first object of the present invention is a vaccine against Chagas disease, capable of stimulating the immune response against the trans-sialidase virulence factor of the parasite Trypanosoma cruzi, the vaccine is distinguished by the fact that it comprises a multicomponent vaccine for the Chagas disease (American tripanosomiasis) comprising: (a) an immunogenic portion formed by one or more recombinant or synthetic polypeptides or fractions thereof and (b) one or more polynucleotides comprising the regions that codifies one or more immunogenic polypeptides, both portions for the Trypanosoma cruzi derivates (i.e., T. cruzi and or a conserved region common to many of them) where the vaccine administration is a protection against the parasite infection, eliminates it or reduces the clinical consequences of the infection.

Another objective of the present invention is a monocomponent vaccine against the Chagas disease that comprises at least one component selected among an immunogenic portion formed by one or more recombinant or synthetic polypeptides or fractions thereof, and a group of polynucleotides including the regions that codifying one or more immunogenic polypeptides derived from Trypanosoma cruzi (i.e. a T. cruzi and/or a conserved region common to many of them) where the immunogenic portion or the polynucleotides group stimulates an antibody response, of CD4+ Th1 biased T cells or CD8+ T cells against the Trypanosoma cruzi.

This invention also includes the pharmaceutical compositions containing the multicomponent and monocomponent vaccines, the procedures for the obtention of the immunogen portion of said vaccines and the nucleic acid used in said procedure.

FIGURES DESCRIPTION

FIG. 1: SEQ ID NO: 1. Sequence of the nucleotides of the gene region codifying the Trypanosoma cruzi protein having trans-sialidase activity. Letters represent four bases (molecules) that constitute de DNA (deoxyribonucleic acid). A: adenine, T: tymine, C: cytokine, G: guanine Every three bases (bases triplet) codifies an amino acid (molecular unit faulted by the protein) that in this case is trans-sialidase. The ATG indicated in low case is the first amino acid of the trans-sialidase (methionine amino acid). The last TGA triplet is the one used by the cell to indicate where the protein ends (termination triplet).

FIG. 2: SEQ ID NO: 2. Amino acid sequences of the region codified by the gene of SEQ ID NO: 1 showed in FIG. 1 and that corresponds to the part of the protein having trans-sialidase activity. Each letter indicates an amino acid according to the universally accepted code.

FIG. 3: SEQ ID NO: 3. Base sequence codifying the region of repetitive units of amino acids called SAPA. Remaining instructions same as SEQ ID NO: 1 shown in FIG. 1.

FIG. 4 SEQ ID NO: 4. Amino acids sequence codifying according to the base sequence of SEQ ID NO: 3 indicated in FIG. 3 and corresponding to SAPA protein.

FIG. 5: SEQ ID NO: 5. Nucleotides (upper line) and amino acid (lower line) sequence corresponding to the gene and the protein respectively, resulting from the union of trans-sialidase and SAPA.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an efficient vaccine for treating or avoiding the infection of a mammal by Trypanosoma cruzi derivatives (i.e. T. cruzi and/or a conserved region common to many of them). In a preferred embodiment, the vaccine is effective against infection and/or illness caused by T. cruzi. The multicomponent vaccine of this invention is for the Chagas disease (American tripanosomiasis) comprising: (a) an immunogenic portion formed by one or more recombinant or synthetic polypeptides, or fractions thereof, and (b) one or more polynucleotides including the regions that codifying one or more immunogenic polypeptides, both portions for the Trypanosoma cruzi derivates (i.e., T. cruzi and or a conserved region common to many of them) where the vaccine administration is a protection against the parasite infection, eliminates it or reduces the clinical consequences of the infection. One polynucleotide vaccine contains one or more polynucleotides that comprise the regions codifying one or more immunogenic polypeptides derived from T. cruzi. In a similar way, a polypeptide vaccine contains one or more immunogenic polypeptides derived from T. cruzi.

Another objective of this invention is a monocomponent vaccine against Chagas disease comprising at least one component selected between one immunogenic portion is selected from one or more recombinant or synthetic polypeptides, or fractions thereof, and a group of polynucleotides that cover the regions that codifying one or more immunogenic polypeptides derived from the Trypanosoma cruzi (i.e., of a T. cruzi and/or a conserved region common to many of them) where the immunogenic portion stimulates an antibody response of CD4+ Th1 biased T cells or CD8+ T cells against Trypanosoma cruzi.

The “immunogenic portion” of the vaccine may comprise one or more polypeptides, the structure of which includes a C-terminal region which consists of at least two repetitive units; each of those repetitive units shows at least 60% homology to the following amino acid sequence: AHSTPSTPVDSS (SEQ ID NO: 6) and a polypeptide with trans-sialidase activity is fused to the C-terminal region. It may also comprise an adjuvant which does not destroy the trans-sialidase enzymatic activity of the immunogen portion, preferably aluminum oxide. The portion may comprise between 10 and 16 repetitive units in the C-terminal region, preferably 13 units.

The immunogenic portion may be obtained from the Trypanosoma cruzi trypomastigotes (i. e. from a T. cruzi and/or a conserved region common to many of them).

This invention relates to a vaccine that may be a recombinant biomolecule formed by the fusion of that region which consists of repetitive units of amino acids and the polypeptide with trans-sialidase activity and/or the polypeptide with cysteine proteinase activity, and/or the Paraflagelar Rod Proteins (PFR).

The multicomponent vaccine of this invention preferably stimulates an antibody response or an immune response transmitted through cells, or both responses, in the mammal to which the vaccine will be administered. The vaccine preferably stimulated a response of CD4+ Th1 biased T cells or CD8+ T cells. Preferably in the case of a monocomponent vaccine, the vaccine stimulates the antibody response, a response of CD4+ Th1 biased T cells or a response of the CD8+ T cells. A form of especially preparing the vaccine of this invention includes a nucleotide comprising the regions codifying a cytokine, to provide the additional stimulation to the mammal immune system. In a preferred embodiment, the preparation of the vaccine of this invention includes an immunogenic polypeptide which contains a sequence of membrane displacement, to facilitate the introduction of the polypeptide in the mammal's cell and the subsequent stimulation of the immune response transmitted through cells.

The immunogen of this invention may be selected from the TSA-1, ASP-1, ASP-2, hemolysin and Lyt1 proteins.

The multicomponent vaccine of this invention may comprise a plurality of polynucleotides that comprise the regions codifying one or more immunogenic polynucleotides derived from the T. cruzi (of a T. cruzi and/or a conserved region common to many of them) and at least one or more polynucleotides comprising the regions codifying the cytokines that may be selected among interleukin 12 (IL-12), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 6 (IL-6), interleukin 18 (IL-18), γ-interferon, α,β-interferons and chemokines; the IL-12 and GM-CSF cytokines are especially preferred.

The pharmaceutical compositions that contained the recombinant or synthetic polypeptides, or fractions of the immunogenic portion and the polynucleotides including the regions which codifying one or more immunogenic polypeptides derived from the T. cruzi, together with a pharmaceutical carrier are also the object of this invention.

In another embodiment, this invention also provides a vaccine of multiple polynucleotide components. It is prepared by inserting two or more nucleotides comprising the regions which codifying one or more immunogenic polypeptides derived from the T. cruzi in two or more polynucleotide vectors, later combining the polynucleotide vectors to yield a polynucleotide vaccine.

Alternatively, this invention related vaccine may be prophylactically administered to a mammal before the T. cruzi infection. In a preferred embodiment the vaccine application must be efficient to prevent the subsequent infection of the mammal with T. cruzi. In another embodiment the vaccine administration is efficient to prevent the development of the chronic debilitating disease in a mammal after the subsequent infection with T. cruzi. In other embodiment, the vaccine application is efficient to prevent mammal's death after the subsequent infection with T. cruzi.

In another embodiment, the invention includes a method for identify the immunogenic polypeptides of T. cruzi from a T. cruzi library, to be used in a polynucleotide vaccine. In a preferred embodiment, the procedure utilizes the expression library immunization (ELI) in mice to identify the T. cruzi polypeptides that elicit an immune response in a mammal effective to prevent the death, arrest or delay the progression of disease in the mammal that has been infected with T. cruzi. The method is preferably used to identify the immunogenic polypeptides derived from the T. cruzi and from the BALB/c or B6 mice which have been immunized.

In another embodiment the method involves the following:

-   (a) preparing a DNA microarray comprising open reading frame of T.     cruzi genes; -   (b) preparing a first probe comprising Cy3-labeled     trypomastigote-derived T. cruzi cDNA; -   (c) preparing a second probe comprising Cy5-labeled     amastigote-derived cDNA; -   (d) cohybridizing the first and second probes to the microarray to     identify at least one gene whose expression is the T. cruzi during     the intracellular amastigote stage of the infectious cycle, where     the gene codifies a candidate immunogenic T. cruzi polypeptide; and -   (e) immunizing mice with the gene to determine whether the gene     codifies a T. cruzi polypeptide that elicits an immune response in a     mammal effective to prevent the death of the mammal or to arrest or     delay the progression of disease in the mammal associated with     infection of the mammal by T. cruzi.

A form of preparing the immunogen used in the multicomponent or monocomponent vaccines of this invention comprises the following steps: a) bindung the codifying nucleotidic sequences for the immunogenic peptide/s to a vector capable of expressing such sequence, b) linking the codifying sequence obtained in the previous step to a vector capable of expressing such sequence, c) transforming a host capable of expressing the codifying sequence of the immunogen, d) growing the transformed bacteria obtained in the previous step in an appropriate culture medium, e) isolating and purifying the immunogen obtained in the previous step.

Stage b) vector may be pET22b+. The hosts are eukaryote cells, bacteria, especially Escherichia coli BL26DE3, and yeasts. The culture medium of stage d) may be an L-Broth medium.

Another form of preparing the immunogen used in the multicomponent or monocomponent vaccines of this invention comprises the following stages: a) growing trypomastigote form of Trypanosoma cruzi in an adequate culture medium, b) obtaining the supernatant where the trypomastigote forms have grown by centrifugation at 5000 rpm during 10 minutes, c) filtrating the supernatant obtained and passage through an affinity column containing immunoglobulins that recognize the repetitions of the carboxymethyl terminal sequence of the immunogen, d) eluting increasing the pH to detach the protein.

Peptides used in the procedures of this invention may be obtained by chemical synthesis.

Another object of this invention comprises a nucleic acid used in the procedures previously explained because it essentially comprises a sequence codifying said immunogen.

Over 100 natural mammalian hosts are known for T. cruzi-hosts, and T. cruzi can be transmitted to a human from another animal host. Any mammalian host can be immunized according to this invention. Vaccine administration in this application includes humans, domestic animals such as dogs and cats, rodents and wildlife animals. Preferably, the mammal that is immunized is a dog, a cat or a human.

Polynucleotide Vaccine

The polynucleotide vaccine of the invention includes at least one, preferably at least two, nucleotides coding regions, each coding regiong encoding an immunogenic polypeptide component from T. cruzi. When it contains two or more nucleotide coding regions, the polynucleotide vaccine is referred to herein as multicomponent vaccine. It is convenient to minimize the number of different immunogenic polypeptides encoded by the nucleotide coding regions; however, considering that a polynucleotide vaccine generates the highest level of protection, it will codifie 10 or more immunogenic polypeptides. The polynucleotide vaccine contains DNA, RNA, a modified nucleic acid, or any combination thereof. Preferably, the vaccine comprise one or more expression or cloning vectors; more preferably, the vaccine comprises a plurality of expression vectors capable of autonomous expression of a nucleotide coding region in a mammalian cell to produce at least one or more immunogenic polypeptides or cytokine. An expression vector preferably includes a eukaryote promoter sequence, more preferably the nucleotide sequence of a strong eukaryotic promoter operatibly linked to one or more coding regions. A promoter is a DNA fragment which acts as a regulatory signal and binds the RNA polymerase in a cell to initiate the transcription of a downstream (direction 3′) coding sequence; the transcription is the formation of an RNA chain in accordance with the genetic information contained in the DNA. A promoter is operatibly linked to a nucleic acid sequence, or may be used to control or regulate the transcription of that nucleic acid sequence. This invention is not limited to a specific eukaryotic promoter but extends to the wide variety known; preferably, the expression vector includes a CMV or RSV promoter. The promoter used preferably remains as constitutive promoter.

A vector useful in the present invention can be circular or linear, single-stranded or double-stranded and can be a plasmid, cosmid or eposome but is preferably a plasmid. In a preferred embodiment, each nucleotide coding region (whether it codifies an immunogenic polypeptide or a cytokine) is on a separate vector; however, it is to be understood that one or more regions can be present on a single vector, and these regions can be under the control of single or multiple promoters.

Nucleotidic sequences codifying cytokines may be added to the polynucleotide vaccine, such as a granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 12 (IL-12) and the co-stimulating molecules, such as B7-1, B7-2, CD40. Cytokines may be used in several combinations to fine tune the response of the animal's immune system, including both antibody and cytotoxic T lymphocyte responses, achieving a specific level of response needed to control or eliminate the T. cruzi infection. The polynucleotide vaccine may include a fusion product containing an antigenic polypeptide and a molecule, such as CTLA-4, which directs the fusion product to the cells with antigen presence within the host.

Plasmids and other delivery systems are prepared using well known techniques in molecular biology. This invention may include procedures to prepare and use the polynucleotide vaccine.

Polypeptide Vaccine

The polypeptide vaccine of this invention includes at least one—preferably at least two—immunogenic polypeptides from T. cruzi (recombinant or synthetic, or fractions thereof). As with the polynucleotide vaccine, it is desirable to minimize the number of different immunogenic polypeptides supplied in the vaccine; however, it is nonetheless contemplated that a polypeptide vaccine that generates the highest level of protection will contain IQ or more numerous immunogenic polypeptides.

Because a CD8+ T cells response cannot normally be directly triggered by the administration of a conventional protein subunit vaccine, the immunogenic polypeptides contained in the polypeptide vaccine include preferably include one or more membrane transporting sequences (MTS) fused to their N-terminus or C-terminus or both. A membrane transporting sequence allows for transport of the immunogenic polypeptide across a lipid bilayer, allowing it to be delivered to the inside of a mammalian cell.

Cytokines

The Cytokines are proteins which regulate the function of the cells that produce them or other cellular types. They are the agents responsible for intercellular communication; they induce the activation of membrane specific receptors, proliferation functions and cellular differentiation, chemiotaxis, growth and modulation of immunoglobulin secretion. They are basically produced by activated lymphocytes and macrophages, although they may also be produced by polynuclear leukocytes, endotelial cells, epitelial cells and conjunctive tissue cells. Depending on the cell that produces them, they are called lymphokines (liymphocyte), monocynes (monocyte) or interleukines (hematopoietic cells). Their basic action is the regulation of the inflammation mechanism. There are pro-inflammatory and anti-inflammatory cytokines.

Preferably, the polynucleotide vaccine includes at least one nucleotide coding the region codifying a cytokine. Preferred cytokines include interleukin 12 (IL-12), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 6 (IL-6), interleukin 18 (IL-18), γ-interferon, α,β-interferons, and chemokines. Especially preferred cytokines include IL-12 and GM-CSF.

Pharmaceutical Compositions

The polynucleotide and polypeptide vaccines of the invention are readily formulated as pharmaceutical compositions for veterinary or human use. The pharmaceutical composition optionally includes excipients or diluents that are pharmaceutically acceptable such as those that were compatible with the genetic material. The term “pharmaceutically acceptable carrier” refers to a carrier that is acceptable in the sense that it is compatible with the various components of a composition and that does not negatively affect its therapeutical behavior. Suitable excipients are, for example, water, saline solution, dextrose, glycerol, ethanol, or the like and combinations thereof. In addition, if desired, the vaccine may contain minor amounts of auxiliary substances such as wetting or emulsifying agents, pH buffering agents, salts, and/or coadjuvants that enhance the effectiveness of the stimulating composition of an immune response. In this invention some procedures to prepare and use those pharmaceutical compositions are also included.

Administration of a Combination of a Polynucleotide Vaccine and of the Polypeptide Vaccine

This invention comprises the administration of a polynucleotide vaccine and of a polypeptide vaccine to a mammal in a serial protocol. For example, a plasmid-based DNA vaccine may be administered to the primary immune system of a mammal, followed by one or more administrations of a polypeptide vaccine or of a viral vaccine (for example, vector of the vaccine polypeptide that carries the genes that codifies the immunogenic polypeptides and, optionally, the cytokines) to stimulate the mammal's immune system. The order of administration of the various types of vaccines and the nature of the vaccines administered, in any dosage (for example the polypeptide vaccine, plasmid vaccine, viral vector vaccine) may be easily determined by an expert to provoke the most efficient immune response in the mammal.

Definitions of Certain Words and Expressions

“Chagas disease” refers to different clinical expressions in patients infected by different varieties of the T. cruzi, related at the same time to the chronic immunological impact on various white tissues. Consequently, vaccines presently known, either from monkeys or multicomponents from frequently available substances of some T. cruzi type, are partial formulas to undertake a potentially effective treatment in every geographical area where this disease develops, and against every intra o extra-cellular form of the parasite. In addition, the immunogenicity of such common components may vary over time and/or with changes in the host health condition, and therefore, a universal continuous protection is not guaranteed.

“T Lymphocyte” refers to cells (white blood cells) in charge of coordinating the cell-mediated immune response, as well as cooperation functions for the development of every kind of immunological responses, including antibodies response by B lymphocytes. T lymphocytes may be differentiated from B lymphocytes and killer cells due to the appearance of a special receptor in the surface of the membrane, named T-cells Receptor (TCR). T comes from thymus, the most important organ for the differentiation of these cells from mother cells of the lymphatic system.

“CD4+ T cell” refers to T lymphocytes responsible for coordinating cell-mediated immune response, as well as cooperation functions for the development of every kind of immunological response, including antibodies response by B lymphocytes.

“CD8+ T cell” refers to Cytotoxic T Lymphocytes T (CTL); they are included in the T lymphocytes line responsible for the effector function of cell immunity. They neutralize cells infected by intracellular microorganisms, by attacking directly infected cells, injecting toxic enzymes and destroying them. They are currently named CD8+, due to the presence of the CD8 membrane receptor.

CTLs are essentially able to lyse cells when stimulated adequately, especially by antigens expressed on MHC class I. Very specific in their lethal functions, they have the ability to destroy a target cell without affecting surrounding uninfected cells. The cell CTL-mediated destruction process comprises:

-   Recognition of foreign antigen and formation of a stable conjugate     with membrane receptors; MHC-I, TCR, CD8, ICAM-1, LFA-1, among other     receptors and co-stimulators; -   to Activation of CTL cell by means of cell interrelations mediated     by membrane proteins and transduction of intracellular signs; -   Cell lysis compelling to changes in target's cell and exocytosis of     poisoning granules containing principally perforin y granzine; -   Apoptosis of the target cell including the mediation of molecules     inducing cell death, like Fas and its ligand.

Due to the high toxicity of these lymphocytes, and in order to prevent the unnecessary risk of continuous circulation, inactive or virgin cytotoxic cells require two types of triggering signals:

-   Binding of T cells receptor in the membrane of the cytotoxic cell to     Major Histocompatibility Complex (MHC-I) type I on the surface of     cells presenting antigen (CPA), -   Cells infected by microorganisms, preferably intracellular ones     (like viruses), show remnants of the microorganism on their surface     in the context of a MHC-I molecule. The infected cell shows antigens     foreign to a CPA that processes infecting information to CTLs, -   Co-stimulation at high concentrations derived from the binding     between CD40 molecule appearing on membranes of dendritic cells and     their ligand (CD40L) of cytotoxic cells. It is a redundant     interaction, that is to say, the more contacts between CD40 and its     ligand, the greater is the production of ligands by the CTL, turning     triggering signal stronger and more definitive. -   In infected tissues, CTLs recognizing the antigen involved are     activated and retained in the infection area, and they carry out     their effector activity. Those CTLs not recognizing the antigen     involved return to circulation.

The “Immunogenic polypeptide” used in the vaccine against T. cruzi according to this invention refers to the one that can be expressed by T. cruzi in extracellular stage (trypomastigote), in intracellular stage (amastigote), or during both stages of the life cycle. Preferably, the immunogenic polypeptide is expressed by the T. cruzi amastigote in early stage of infection, in approximately 24 hours after initial infection.

A type of polypeptides exemplifying immunogenic polypeptides according to the invention is from the family of the trans-sialidase proteins, such as TSA-1 (T. cruzi Peru; D. Fouts et. al. Mol. Biochem. Parasitol. 46:189-200 (1991); GenBank. Acc. Number M58466), ASP-1 (T. cruzi el Brazil; M. Santos et al. Mol. Biochem. Parasitol. 86:1-11 (1997): GenBank. Acc. Number U74494)) and ASP-2 (T. cruzi el Brazil; H. Low et al. Mol. Biochem. Parasitol. 88:137-149 (1997); GenBank. Acc. Number U77951).

Advantages of this Invention

This invention is the most complete multicomponent or monocomponent vaccine that may constitute varieties of the same component of different T. cruzi, especially of those portions conserved and/or with the addition of targets different among them, for example taking as a target one or several trans-sialidases, fragellar proteins or cysteine proteases from one or more varieties of T. cruzi.

Chagas is a disease requiring incentives and protection for the development and distribution investments; therefore there is no room for a competitive, multi-optional market, as if an Argentine vaccine, a Brazilian vaccine, a Peruvian vaccine, etc. co-existed; in practice, presently known vaccines could not be developed without leaving unprotected an important part of the population affected. Consequently the invention involves the maximum immunogenicity combination facing the variety of clinical expressions (that is, a “monoshot-continental” vaccine).

A formula is proposed to be used against all varieties and clinical expressions. Formulas with such wide range of multicomponents have not been described up to this date.

Advantages of a Genetic Vaccine

Choosing the administration of the polynucleotide as an immunization technique offers an excellent advantage over the different systems that supply other vaccines or antigen delivery systems. Vaccines containing genetic material are preferred over traditional vaccines because vectors are easy to construct and produce, the potential for the modification of mutagenesis sequences directed to enhance antigenic potency of individual epitopes, or to abolish epitopes that might trigger an unwanted response. In the case of DNA vaccines, DNA stability, the lack of the risks associated to live and attenuated vaccines, their ability to induce humoral immunity and cell transmitted immunity, and, particularly, CD8+ T cell responses, and persistence of the immunity responses.

It has also been demonstrated their ability to improve immunity response by the co-administration of genes codifying cytokines.

TABLE 1 TS activity in serum following intravenous injection of trans-sialidase protein (TS) or SAPA-bound trans-sialidase (TS-SAPA). Hours post-inoculation 0.5 16 26 110 TS* 100% 3% 0% 0% TS-SAPA* 100% 60% 50% 5% Values are averages obtained from three independent animals per group. Measuring was carried out on serum samples collected from each mouse at 30 minutes, and 16, 26 and 110 hours following inoculation. The mouse strain used was C3H. *Values expressed in % activity of remaining trans-sialidase considering as 100% the values obtained 0.5 h following TS immunization (for TS values) or with TS-SAPA (for TS-SAPA values) respectively.

If instead of injecting a protein with trans-sialidase activity, a mouse is intravenously injected a protein containing the region with trans-sialidase activity bound to SAPA protein (TS-SAPA), results obtained are different (Table 1). When samples are collected at different times following intravenous injection, trans-sialidase activity is detectable up to 5 days after the injection. These results show that SAPA protein, when bound to another protein like trans-sialidase, is conferred a new property: the property of stabilizing it in blood, maintaining this enzymatic activity in circulation for a longer time.

Results similar to those described above may be obtained when other routes of administration, such as, intramuscular, intraperitoneal, subcutaneous or any other triggering an antibody response in the immunized host are used instead of the intravenous route of administration. Similar results can be obtained as well when some of the already known immunizing adjuvants are used, such as aluminum oxide or others not destroying the enzyme, as detailed below. An adjuvant is either an oily or aqueous substance, or a substance with another structure that injected jointly with the immunogen—in this case a recombinant protein like trans-sialidase/SAPA-contributes to increase immunogenicity, that is, increases the immune system response related to antibodies production or cell response. A cell response is a type of response by the immunologic system where basically the cells contributing to control an infectious agent proliferate.

Another result obtained from these experiments is that a response against trans-sialidase inhibiting its activity is only obtained when this enzyme is used as an immunogen in its active form, that is, with a conformation that retains its enzymatic activity.

TABLE 2 Inhibiting activity of the trans-sialidase in serum of animals immunized with trans-sialidase, with repetitions (TS-SAPA), with Freund's adjuvant (AF), with aluminum oxide (Al₂0₃) or with protein denaturalized by heat at 80° C. (80° C.) Immunization was carried out by intraperitoneal route, in all cases with 65 nanogrames for the first dose (day 0) and with 13 nanogrames for the second dose on day 38. Trans-sialidase inhibition measure was carried out as described for the experiments previous to day 1 and on day 45 after the first immunization (day 0). The measure is expressed in % of the inhibition obtained in the presence of serum of non immunized mice, the inhibition values of which are considered 0. The values are the average obtained from four immunized mice independently for each condition. Days after immunization 1 45 TS-SAPA in AF 0% 0% TS-SAPA in Al₂0₃ 0% 90% TS-SAPA at 80° C. 0% 0%

Another result obtained as a consequence of these experiments is that only a response is obtained against the trans-sialidase that inhibits its activity when this enzyme is used as immunogen in its active formulation, that is, with such a conformation that it keeps its enzymatic activity. Table 2 shows that when the adjuvant used to immunize mice is aluminum oxide—which does not alter the enzymatic activity of trans-sialidase—antibodies which inhibit it are generated. However, if Freund is used as adjuvant—which destroys the enzymatic activity of trans-sialidase, no antibodies inhibiting trans-sialidase will be generated in the mouse. Likewise, heat-inactivated trans-sialidase at 80° C. for 3 minutes so as to avoid protein from maintaining it enzymatic activity, preventing it from being stimulated by the formation of neutralizing antibodies.

Results similar to those described above may be obtained when other routes of administration, such as intramuscular, intraperitoneal, subcutaneous or any other triggering an antibody response in the immunized host are used instead of the intravenous route of administration.

Furthermore, similar results may be obtained when some of the adjuvants known to immunize, such as aluminum oxide or others which do not destroy the enzyme, as mentioned before. An adjuvant is oily, water, or other structure substance, that injected together with the immunogen, in this case a recombinant protein, such as trans-sialidase/SAPA, contributes to increase its immunogenicity, that is, it increases the response of the immune system as regards antibodies production or cell response. Cell response is a type of response of the immunologic system where proliferation is basically of cells contributing to control an infectious agent.

There is no doubt that once this invention is put into practice, some modifications may be introduced regarding construction and shape details; this will not imply straying away from the fundamentals that are clearly expressed in the claims that follow. 

I claim:
 1. A monocomponent vaccine effective to moderate the clinical consequences of Chages disease, said vaccine comprising, as active ingredient, an immunogenic component comprising a polynucleotide encoding one or more polypeptide(s) which includes a C-terminal region composed of at least two repetitive units of amino acids, wherein each repetitive unit shows the following amino acid sequence: AHSTPSTPVDSS and wherein a polypeptide with trans-sialidase activity of Trypanosoma cruzi is fused to the C-terminal region, and wherein the vaccine further comprises an adjuvant that does not inhibit trans-sialidase enzymatic activity of the immunogen portion, wherein the adjuvant is aluminum oxide.
 2. The monocomponent vaccine of claim 1, wherein the C-terminal region of the immunogenic component is encoded by a polynucleotide having the nucleotide sequence of SEQ ID NO.
 3. 3. The monocomponent vaccine of claim 1, wherein the polypeptide with trans-sialidase activity of Trypanosoma cruzi has the amino acid sequence of SEQ ID NO. 2 and is encoded by the nucleotide sequence of SEQ ID NO.
 1. 4. The monocomponent vaccine of claim 1, further comprising one or more polynucleotides that comprise the regions which encode cytokines.
 5. The monocomponent vaccine of claim 4, wherein the cytokine is selected from interleukin 12 (IL-12), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 6 (IL-6), interleukin 18 (IL-18), γ-interferon, α,β-interferons and chemokines.
 6. The monocomponent vaccine of claim 5, where the cytokine is selected from the IL-12 and GM-CSF cytokines.
 7. The monocomponent vaccine defined in claim 1, wherein the immunogenic component is selected from between 10 and 16 repetitive units in the C-terminal region.
 8. The monocomponent vaccine defined in claim 1, comprising a recombinant biomolecule formed by the fusion of that region which comprises repetitive units of amino acids and at least one of (i) the polypeptide with trans-sialidase activity, (ii) the polypeptide with cysteine proteinase activity, and (iii) the paraflagellar rod protein (PFR).
 9. The monocomponent vaccine defined in claim 1, wherein the immunogen of the immunogenic component is obtained from Trypanosoma cruzi trypomastigotes.
 10. The monocomponent vaccine defined in claim 1, wherein the immunogen of the immunogenic component is obtained from Trypanosoma cruzi amastigotes.
 11. The monocomponent vaccine defined in claim 1, which stimulates at least one immune response selected from an antibody response and an immune response by cell mediation.
 12. The monocomponent vaccine defined in claim 11, which stimulates at least one response of CD4+ Th1 biased T cells and CD8+ T cells.
 13. The monocomponent vaccine defined in claim 12, which stimulates at least one response CD8+ T cells.
 14. The monocomponent vaccine defined in claim 1, wherein the polypeptide is selected from the TSA-1, ASP-1, ASP-2, hemolysin and Lyt1 proteins.
 15. The monocomponent vaccine of claim 1, wherein said vaccine is a therapeutic vaccine.
 16. The monocomponent vaccine defined in claim 1, wherein said vaccine is a prophylactic vaccine.
 17. The monocomponent vaccine defined in claim 1, wherein the C-terminal region of the immunogenic component is a polypeptide having the amino acid sequence of SEQ ID NO.
 4. 18. A monocomponent vaccine comprising, as active ingredient, an effective amount of a polynucleotide codifying one or more immunogenic polypeptides derived from a Trypanosoma cruzi.
 19. The monocomponent vaccine defined in claim 18, comprising a recombinant biomolecule formed by the fusion of that region which comprises repetitive units of amino acids and at least one of (i) the polypeptide with trans-sialidase activity, (ii) the polypeptide with cysteine proteinase activity, and (iii) the paraflagellar rod protein (PFR). 